The present application relates to hydraulic systems, and more particularly to an absorber-replenisher apparatus in hydrostatic circuits in a drilling rig.
During the extend cycle of a single rod hydraulic cylinder in a hydrostatic circuit, a large quantity of fluid flow is required to make up for the loss of fluid flow due to the differential area of the two sides of the single rod cylinder piston. During the retract cycle, the same fluid flow must be diverted to the reservoir. The ratio of the volume on either side of the hydraulic cylinders changes as the cylinder extends or contracts.
Typically in prior art designs, when extending, a large auxiliary pump is used to provide the fluid flow making up the differential oil loss. When retracting, the fluid flow from the pump is diverted through a relief valve along with the surplus fluid to make up the differential oil loss. The amount of energy wasted (i.e., power lost) is a function of the total fluid flow and the replenishing relief pressure setting. Such a setup adds complexity to the hydrostatic circuit.